In the colder climates of North America and other parts of the world, snow plows are required for plowing large areas, such as local roads, highways, parking lots, airports, and commercial and residential driveways.
In order for the snow removal equipment, such as pick up trucks or heavy-duty snow plowing machines, to run efficiently at relatively high speed, the plows must scrape the road surface to remove the accumulated snow and ice. During such operations, the plows and sometimes the vehicles can be heavily damaged if the plow strikes a rigid transverse road projection.
Snow plow shoes or supports have been developed as a sacrificial member to bear most of the loads and impacts resulting from the snow plowing operation. The shoes are installed slightly beneath the bottom surface of the plow to raise the height of the plow above the ground level so that potholes, ice mounds, and other obstacles do not impact the plow directly and cause expensive or irreparable damages. Extreme and frequent wear of support structures and wear pads or shoes equipped for use with street sweepers, snow plows, snow blowers and other such utility vehicles is a costly and time consuming maintenance problem, requiring intensive labor and frequent downtime. Many design changes and various materials have been tried to minimize the frequency of maintenance, resulting in minimal improvement.
Snow plow shoes are generally made from cast iron or steel and the blades are made from forged or hot rolled steel plates. Shoes and blades made from plain carbon or alloy steel may wear out after a relatively short time. The rugged and continuous use of snow plows for hours at a time in removing snow from paved and un-paved road surfaces makes it difficult for the cast iron or steel shoes and blades to last for at least one season. Generally speaking, shoes are replaced a few times a season, depending on the usage. Snow plow shoes are especially prone to wear out faster, because they bear a large portion of the load from the snow plow. Snow plow shoes and blades must withstand large stresses and repeated jarring action. Even relatively smooth layers of snow, ice or even exposed ground can be highly abrasive under certain conditions. Also the steel products are prone to corrosion. Salt and snow (moisture) make the steel components more prone to corrosion, resulting in fretting wear, in addition to regular wear and abrasion.
To address these problems, various methods have been employed over many years but without any significant success. Attention must be paid to use durable and reliable materials for movable components, which are subject to wear and are exposed to the harsh elements. The present invention provides some selected advanced structural ceramic materials which have unexpected advantages in improving the performance and reliability of such snow removal equipment, although it may not be intuitively apparent to many materials specialists. This is because most of the conventional high performance advanced structural ceramics are extremely brittle. An example of a material having high hardness and superior strength (elastic modulus) is monolithic cubic spinel. This material, however, is also highly brittle and is practically unusable for this type of rugged structural applications. Those skilled in the art are more inclined to experiment with alternative metallic components, especially high strength steel or very hard carbide (generally cermets like Ni or Co bonded tungsten carbide).